1. Field of the Invention
The present invention relates to a vehicle-height adjustment apparatus of a motorcycle.
2. Description of the Related Art
Desirably, vehicle height of motorcycles are relatively low such that even short riders can easily set their feet on ground as this prevents motorcycles from falling down at the time of stopping. On the other hand, motorcycles are required to have a certain degree of vehicle height from the viewpoint of bank angles, shock absorption, or the like at the time of running. In addition, some motorcycles for the market in America are designed to have a low vehicle height when they are not running so that they meet market needs in terms of appearance
In view of this, there have been proposed the vehicle-height adjustment apparatuses of motorcycles as described in Japanese Examined Patent Publication No. H8-22680 and Japanese Patent Application Laid-open No. 2000-145873. The vehicle-height adjustment apparatuses have: a damper tube that is provided on one of a vehicle body and an axle; a piston rod that is provided on the other one of the vehicle body and the axle and performs extension and compression movements relative to the damper tube by sliding in an oil chamber inside the damper tube; a hydraulic jack, is provided on one of the damper tube and the piston rod; a suspension spring that is interposed between a spring bearing supported by a plunger inserted in the jack chamber of the hydraulic jack and a spring bearing provided on the other one of the damper tube and the piston rod; a hydraulic pump that is caused to perform a pumping operation by the extension and compression movements of the piston rod relative to the damper tube to supply and drain the oil of the oil chamber inside the damper tube to and from the jack chamber of the hydraulic jack; and a switching valve that is closed such that the operating oil supplied to the jack chamber of the hydraulic jack is stopped, or is opened such that the operating oil is discharged. The vehicle-height adjustment apparatuses are capable of adjusting a vehicle height by the extension and compression movements of the piston rod relative to the damper tube.